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Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 11078
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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I got a 2001 Mercruiser 5.7. I get a weak spark to 10

Customer Question

Customer: Hi,My name is ***** ***** a 2001 Mercruiser 5.7. I get a weak spark for 5 to 10 seconds and then no spark at the coil.
JA: Thanks. Can you give me any more details about your issue?
Customer: I have replaced all sensors including ignition module and coil and still have the same problem
JA: OK got it. Last thing — JustAnswer charges a fee (generally around $26) to post your type of question to Boat Experts (you only pay if satisfied). There are a couple customers ahead of you. Are you willing to wait a bit?
Customer: ok i ll wait
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Submitted: 1 year ago.
Category: Boat
Expert:  Tan replied 1 year ago.

Hello Gus. My name is Tan.

Do you have a volt meter to check for voltage at the ignition coil + purple wire when cranking?

Could I get the engine serial number please? They used different ignition systems on different models of the 5.7 so I need serial number to know which one you have.

Customer: replied 1 year ago.
Hi Tan thank you for getting back to me
serial number 0M008189,purple wire reads 9 to 10 volts but only for like five seconds
Expert:  Tan replied 1 year ago.

Ok we need to check the voltage at the key switch when cranking the engine do you loose voltage there?

If no then we need to go to the kill switch and check voltage there. Do you loose voltage? If no then we need to disconnect the plug at the engine where the boat harness connects to the engine harness. Pull the plug apart and check all the pins are clean and straight. Put plug back together and retest.

Post back with findings.

Customer: replied 1 year ago.
didn't have a chance to try on that yet, will let you know if it worked as soon as I try it. Thank you.
Expert:  Tan replied 1 year ago.

Ok Gus keep me posted no rush.